Method and apparatus for airborne ultrasonic testing of package and container seals

ABSTRACT

A method for testing or inspecting the integrity of package closure seals using contact and non-contact ultrasonic systems wherein a relative movement is created between a package seal and at least one ultrasonic transmitting transducer and at least one receiving transducer such that ultrasonic energy is focused so as to be transmitted toward and along a length of the seal from the transmitting transducer to the receiving transducer in a gaseous environment to thereby monitor energy signals which are analyzed to provide an indication of the seal integrity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is generally directed to methods and systems forintegrity testing of seals associated with various packaging orcontainers and more specifically to a method and system for utilizingairborne or a combination of airborne and contact ultrasonic energywhich is transmitted through a gaseous medium, such as air, to a sealfrom a transmitting transducer. A receiving transducer receives energywhich either passes through the seal or is reflected therefrom andsupplies signals to an analyzer or computer which provides output withrespect to the seal integrity.

2. Brief Description of the Related Art

The non-contact, non-destructive and non-invasive inspection of theintegrity of seals used in the packaging industry, and especially thoseused in packaging food, medical devices and pharmaceuticals, is becomingincreasingly more important to ensure that the contents of packagedproducts remain suitable for use to thereby protect the health andwelfare of consumers. In this respect, the industry provides forselectively testing of different product packaging including flexiblepouches, trays, cups, blister packs, bottles and the like to ensure thatthe seals associated with such packages are free of faults or flaws.Such faults may be voids in a seal, inclusion of contaminants along aseal or closure, uneven and marginal heat seals, seals of insufficientsize or width, delaminations in areas of a seal, and other sealcharacteristics associated with bonded materials utilized in thepackaging industry.

There are numerous types of container filling and sealing machinescurrently used in the packaging industry. For example, vertical pouchfilling and sealing machines are utilized to fill products through anopening in a top of the pouch afterwhich the pouch is sealed, cut anddropped onto a take away conveyor. Periodic or sequence testing of theseals is required to ensure that packages are free of contamination orfaults.

Horizontal filling and sealing machines are used to either continuouslymove or periodically index packages which are filled from the topafterwhich a heat seal is provided using stationary or moving heatsealing jaws. The jaws may be associated with a heat sealing rollersystem. Seal testing is performed after sealing.

Certain type of pouches incorporate zipper or interlocking type closureswhich may be located adjacent to a heat seal. In order to preventleakage, a zipper component on either side of the pouch is sealed bypressure and heat.

Form filled seal machines form a lower part of a package into a cavityand then load and fill a product into the package cavity and then seal atop layer onto the lower cavity or tray. This process is typically donein an indexing motion from one to several stations along a conveyor. Theshape of the tray may be in-any form, however, most are rectangular,square or round.

Regardless of the type of product filling and sealing machines used,inspection of packages following filling and sealing is critical toensure the integrity of the seals and thus the suitability of thepackaged product for later use or consumption. Often, because packagesare filled at high speed under critical conditions, a product maycontaminate the area of a seal and thus interfere with an effectiveseal. Further, sealing tools can become contaminated, misadjusted orworn and can lead to the formation of bad or faulty seals during thepackaging sealing process. In view of the foregoing, it is necessary toprovide a method for inspecting and determining the integrity ofpackaging seals before product is shipped to consumers.

There are currently and in the industry a number of methods and devicesfor testing the integrity of seals associated with packages havingdifferent types of closures. The most basic testing procedure is throughmanual inspection of packaging, either visually, by touch, feel ordestructive means. Manual inspection is suitable to determine obviousproblems associated with packaging, such as a missing or partiallyapplied lid, a separated seal, a ruptured or damaged container orclosure and the like. Manual inspection, however, is not efficient,provides no variable data and is not effective to determine sealcharacteristics such as contaminations, voids in seals, delamination ofseal layers, micro-holes or defects in a seal and like. To reduce costswhile providing greater effectiveness in inspecting package seals,automated procedures and systems have been developed to inspect or testseals.

Such automated testing procedures have included the use of devices forapplying pressure to packages which are carried along a conveyor. Thedegree of deflection of a package, or the amount of recovery a lid orwall of a package, after pressure is applied, is measured to determinewhether or not leaks are present in either the packaging materials or inthe seals associated therewith. Other types of physical tests includemeasuring package weight gain or loss, monitoring lid or closuredeflection to determine if proper internal pressure is obtained andmaintained in a package, the use of tracer gases such as a carbondioxide, oxygen and helium, and electrical conductivity.

Other types of leak testing systems incorporate vacuum sources indifferential and absolute pressure sensory systems. Packages are placedwithin chambers and vacuums are applied such as to create a differentialpressure between an interior of a package and the surrounding vacuumchamber. Pressures within the testing chambers can be monitored so as todetermine if there are changes in pressure after vacuums or partialvacuums are applied to thereby give an indication of a faulty seal orleak.

In U.S. Pat. No. 5,513,516 to Stauffer, A Method And Apparatus ForTesting A Container System is disclosed which incorporates a vacuumchamber in which a flexible or semi-flexible package is cooperativelyreceived. A flexible wall or membrane is provided within the testingchamber and designed to provide a sealing surface against a wall of thecontainer. The use of the flexible wall or membrane allows inspection ofpackaging formed of gas permeable materials to be tested such that,during the testing process, pressure differentials are only due to leaksalong the package seals, and not the packaging material.

Some of the problems associated with prior art pressure type testingchambers for use in the packaging industry to ensure the integrity ofpackaging seals is that the packages must be placed within a supportingchamber, afterwhich a change is made to the atmosphere surrounding thepackage seal. In instances where pressure is applied by mechanicalforce, leaks can be plugged or covered and contamination can occur topackages as well as cross-contamination between packages. Further, thenumber of steps necessary to complete a seal test limits the effectivenumber of containers or packages which can be tested or inspected at anygiven period of time and potential leaks, plugged leaks or weak sealsare not detectable.

A further type of automated and testing system uses ultrasonic energywhich is directed through a package seal in a liquid medium, such aswater. Sealed containers are placed in a testing apparatus where aliquid is used to ultrasonically couple an ultrasonic transmitter arrayand a receiver array to the container rim. Using such a system, theliquid must be introduced around the seal in order to allow ultrasonicenergy to be effectively transmitted through the seal and be detected bythe receiver array. Thereafter, the liquid must be drained off and thepackage removed from the apparatus. Because of the requirement for aliquid environment, such ultrasonic systems are considered destructivein most cases and have not proven to be efficient and adequate fortesting with respect to many container seals.

One of the essential features of any testing method and apparatus isthat it must be economical to the manufacturer to use so that the costof products are not increased, such as by limiting production due toslow testing procedures. In light of the foregoing, there remains a needto provide an apparatus and procedure for testing package seals whichincorporates testing procedures which facilitate the manner in whichpackage seals can be inspected to ensure their integrity and whereinsuch testing procedures and apparatus can be used efficiently so thatproducts can be tested rapidly along a product filling line withoutadversely effecting the overall economics of the packaging system.

SUMMARY OF THE INVENTION

The present invention is directed to methods and devices for inspectingpackage seals utilizing both contact and non-contact ultrasonic energysystems which include at least one ultrasonic transmitting transducerand one ultrasonic receiving transducer, which may, in some instances bethe same transducer, which are operable in a gaseous environment, suchas under ambient conditions within a product packaging and/or sealingfacility. Following the filling and sealing of a package or container,which may be of any of the types previously described, as well asothers, the seal of the package is directly exposed to ultrasonic energywhich is passed through it, or reflected from it, and along the lengthof the seal from the transmitting transducer such that the ultrasonicenergy is received by the receiving transducer. The receiving transduceruses the energy received to produce signals which are analyzed toprovide an indication of the integrity of the seal. In some embodiments,the package or container may remain stationary and a plurality ofairborne ultrasonic transmitting transducers may be aligned along thelength of the seal, regardless of its shape, with a plurality ofreceiving transducers used to measure the energy passing through theseal or reflected from the seal. In other embodiments, one or moretransmitting transducers may be movably mounted relative to a stationaryproduct container so that the transducers are moved to transmit energyalong the length of a seal and wherein one or more receiving transducersare simultaneously moved or concurrently moved with the transmittingtransducer or transducers to receive ultrasonic energy in order toproduce the signals which give an indication of the seal integrity.

The methods of the invention may be used to effectively determine theintegrity of not only heat seals but also glued or otherwise welded typeseals utilized in the container or packaging industries. The transducersnormally operate in frequency ranges of 100 KHZ to 5 MHZ. The materialsto be joined can be any type of single or multi-layer plastic films,papers, aluminum foils and composite material structures, orcombinations thereof.

In some embodiments, the energy from the ultrasonic transmittingtransducer is focused to a defined shape relative to a seal in order toprevent the passage of ultrasonic energy around an edge of a package,especially where the edge of the package is spaced closely adjacent tothe seal. This prevents any wrap around ultrasonic energy from adverselyeffecting the results detected by a receiving transducer which is spacedon an opposite side of the seal which could give a false indication ofthe integrity of the seal being tested. Some focusing devices may bebarriers through which ultrasonic energy is transmitted or may bereflectors which concentrate the ultrasonic energy upon reflection froma predetermined surface toward and through a container seal.

In some embodiments of the invention, the edge of a package adjacent aseal may be passed through a guide such that the seal moves along afixed path so as to pass between one or more fixed transmittingtransducers and one or more receiving transducers.

In yet other embodiments, in order to prevent the stray or wrappedultrasonic energy from effecting the readings of a receiving transducer,an edge of a package adjacent to a seal being tested may be screened orabutted by a shield member which, in some embodiments, may beresiliently mounted such that the shield rides along the edge of thepackage adjacent to the seal during seal testing. Such shields may beformed of rollers or wheels which track along an edge of a package.

The methods and systems of the present invention are specificallydesigned to permit ultrasonic testing in gaseous environments such as inambient air conditions. In some embodiments, both the transmitting andthe receiving transducers will be spaced at a predetermined distancefrom a package seal such that the ultrasonic energy is transmittedthrough a gaseous median to the seal. Much of the ultrasonic energy willbe reflected from the seal, such as at areas between laminates of theseal, with only a small portion passing through the seal to thereceiving transducer. In other embodiments, either the transmittingtransducer or the receiving transducer may be in contact with a portionof the package adjacent to the seal during the seal inspection.

In yet a further embodiment of the present invention, the transmittingtransducer and the receiving transducer may be positioned on the sameside of a package seal being inspected such that ultrasonic energy isreflected off the seal area or off the laminates forming the seal fromthe transmitting receiver to the receiving transducer. In some otherembodiments, the transmitting receiver may be electrically controlledsuch as to function as both a transmitting and a receiving transducersuch that ultrasonic energy reflected from the seal area is received bythe transmitting transducer.

In yet a further embodiment of the present invention, either thetransmitting transducer or the receiving transducer may be moveablerelative to a seal area, such as by forming the transducer in aconfiguration of a wheel which can rotate along the length of the sealwith the wheel transducer being in contact with the package adjacent tothe seal during seal inspection.

Using the method and systems of the present invention, inspection ofpreformed pouches, packages, trays, cups, bottles and other containerswhich are filled and sealed individually, can be accomplished at speedsup to or exceeding 200 to 500 units per minute.

The system of the present invention may also be used with proprietaryself-learn algorithm software in combination with digital processors orcomputers which process initially received signals from a receivingtransducer in order to continuously update information with regard toseal integrity. Preliminary setting of an analyzing computer or digitalsignal processor can be accomplished by passing a plurality good samplesbetween the transmitting and receiving transducers and allowing theanalyzer to detect and effectively learn the limits defined by goodseals. In a like manner, seals having known defects, either by way ofdelamination, holes or openings in seal areas, insufficient seal widths,contaminated areas and the like can be passed between the transmittingand receiving transducers with the seals being analyzed so that thecomputer effectively creates data files for specifically identifying atype of seal flaw which may be encountered during testing. The systemsfor accomplishing such ultrasonic testing and proprietary self-learnalgorithm procedures are disclosed in U.S. Pat. No. 6,343,510 to Neesonet al., the contents of which are incorporated entirely herein byreference and U.S. Pat. No. 6,311,573 to Bhardwaj, the contents of whichare also incorporated in their entirety herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention will be had with respect to theaccompanying drawings wherein:

FIG. 1 is a partial side illustrational view showing a system of thepresent invention wherein a package in a form of sealed tray is tested;

FIG. 2 is a top plan view of the system of FIG. 1 showing movement ofthe package relative to the testing system;

FIG. 3A is an illustrational view of the package of FIG. 1 beingadvanced between a filling, heat sealing and inspection station inaccordance with the teachings of the present invention;

FIG. 3B is a top plan view of a modification of the testing system ofthe present invention;

FIG. 4 is a modified embodiment similar to that disclosed in FIG. 1;

FIG. 5 is an alternate embodiment of the invention utilizing thetransducer system generally shown in FIG. 1;

FIG. 6 is a cross sectional view of the pouch shown in the embodiment ofFIG. 5 mounted within a carrier;

FIG. 7 is a top plan view of the embodiment of FIG. 6;

FIG. 8 is a side illustrational view of a variation of the embodimentshown in FIG. 5;

FIG. 9 is a partial illustrational view showing a further variation ofthe embodiment of FIG. 9 for focusing energy between the transmittingand receiving transducers;

FIG. 10 is a cross sectional view of another embodiment of theinvention;

FIG. 11 is a cross sectional view taken from the top of the embodimentof FIG. 10 showing a variation for guiding a pouch relative thereto;

FIG. 12 is a cross sectional view of a further variation of theembodiment shown in FIG. 10;

FIG. 13 is a variation of the embodiment of the invention shown in FIG.1 shown in cross section;

FIG. 14 is a partial cross-sectional view taken through an ultrasonicinspection head wherein energy from the transmitting transducer isfocused toward a seal and a receiving transducer through adjustablefocal plates;

FIG. 15 is a cross-sectional view taken along line 15—15 of FIG. 14;

FIG. 16 is a partial side illustrational view of an embodiment of theinvention in which a transmitting transducer is in contact with apackage adjacent to a seal with the receiving transducer being in spacedrelationship from the seal in a gaseous environment;

FIG. 17 is a view similar to FIG. 14 except showing the receivingtransducer in surface contact with a package or pouch adjacent to a sealarea wherein ultrasonic energy is transmitted from a transmittingtransducer spaced from the package;

FIG. 18 is an illustrational view of another embodiment of the inventionwherein, in solid line, a single transducer element is utilized as atransmitting and a receiving transducer in accordance with the inventionand wherein, in dotted line, a transmitting transducer and receivingtransducer are shown being oriented on the same side of a seal beinginspected; and

FIG. 19 is a partial side illustrational view of another embodiment ofthe invention wherein the transmitting transducer is shown as being arolling element capable of tracking along a package adjacent to a sealarea.

DESCRIPTION OF PREFERRED EMBODIMENTS

With continued reference to the drawing figures. The present inventionwill be described with respect to the use of both contact andnon-contact airborne ultrasonic transducers to test or inspect theeffectiveness or integrity of seals associated with numerous types ofproduct packaging. The system and method utilized in the presentinvention can be used to test different product packaging includingflexible pouches, formed trays, cups, blister packaging, plasticbottles, Tyvek™ containers and the like. For purposes of illustration,only some types of containers or packages will be described withreference to the drawing figures.

Packages or containers which can be inspected utilizing the systems andmethod of the present invention may be formed of many of a plurality ofmaterials or composites including such materials as plastic films,laminates, papers, metal foils and the like. The seals may be formed bysubstantially any process including adhesive, welding, heat and pressuresealing and the like.

A first embodiment of non-contact ultrasonic testing system whereultrasonic energy is passed through a seal of a container in a gaseousenvironment is shown in FIG. 1 at 20. The system includes at least oneultrasonic energy transmitting transducer 21 and at least one receivingtransducer 22. The transmitting transducer and receiving transducer arealigned relative to a seal area “S” adjacent an edge “E” of the package,such as a tray “T”, and both transducers are spaced in non-contactingrelationship from the package or tray. The transducers are axiallyaligned with respect to one another so that ultrasonic energy “U”transmitted from the transmitting transducer 21 passes through the seal“S” after which energy “U2” is received by the receiving transducer 22.The transmitting transducer receives energy from a frequency generator23. The receiving transducer develops a signal which is passed by way ofelectrical connection to a computer analyzer 24 wherein the receivedsignal is analyzed in order to determine the integrity of the seal “S”.Information from the analyzer can be used to provide input to acontroller 25 such that a conveying line “C” on which the tray iscarried can be controlled. If a flaw or defect in a seal is detected,the tray can be ejected from the product packaging line. In theembodiment shown, the transmitting transducer 21 is fixedly mounted to asupport 28 while the receiving transducer is fixedly mounted to asupport 29. This on-line inspection is done in linear-scan mode (L-Scan)emitting and analyzing signals as the seal passes between thetransducers. Alternatively, one can analyze an entire heatseal with theC-Scan mode, which represents a micro acoustic image of multiple L-Scansdone in a X-Y scan motion. The ultrasonic signals are converted into acolor chart, representing a digital image of the seal area.

During the ultrasonic testing, the ultrasonic waves will be primarilyreflected at the interface of the different material or laminates fromwhich the package seal is formed. The reflected energy is greater thanthe amount of energy which passes through the seal. Therefore, a goodseal allows only a very small portion of the transmitted energy to bereceived by the receiving transducer, with most of the energy beingreflected from the surface of the container and from the interfaces ofthe layers of the different materials forming the seal, such as aluminumfoils and plastic or paper layers. If the seal has delaminations,inclusions of air are other foreign materials therein, there is createdadditional interfaces that function as reflective barriers for theultrasonic waves such that energy received by the receiving transducerwill drop more than would be anticipated with a good seal.

In those instances wherein two portions or laminates of a seal are notappropriately aligned after sealing, the missing layer of the seal wouldcreate less of a barrier to the ultrasonic waves passing therethroughsuch that a signal at the receiving transducer would be increased.

After a product has been filled withing the tray “T” and a closure orlid “L” applied thereto, the package or container passes through anappropriate sealing device which provides a seal adjacent the peripheraledge “E”, as shown in FIG. 3A. The package then passes by way of theconveyor “C” to the testing station 20 wherein the seal is alignedbetween the transmitting transducer 21 and the receiving transducer 22.

With specific reference to FIG. 2, to test the entire length of theseal, the tray may be rotated relative to the transmitting transducerand receiving transducer, as is illustrated by the arrow in the figuresuch that the entire seal area “S” is tested by the passage ofultrasonic energy through a gaseous medium, such as air, which surroundsthe seal and such that the entire length of the seal is analyzed toensure that there are no flaws. In this embodiment, the conveyor “C”would include a rotatable section which would be indexed in the manneras shown by the arrow in FIG. 2 when the tray is aligned within thetesting station 20, as shown in FIG. 1.

As opposed to moving the tray relative to the testing transducers, it isalso possible that the transducers may be mounted on movable supports asopposed to fixed supports. In this event, the transmitting transducerand the receiving transducer would be moved relative to the seal “S” ofthe tray “T” and about is full periphery.

In addition to the foregoing, as opposed to using only a single set oftransmitting and receiving transducers, a plurality of such transducersmay be positioned around the periphery of the seal area in order tofurther facilitate the testing procedure and to reduce the timenecessary to fully analyze the full length of a seal.

The energy transmitted from the transducer 21 generally is in the rangefrom 100 KHZ to 5 MHZ. A preferred transducer system operable in agaseous or airborne environment is disclosed in U.S. Pat. No. 6,311,573to Bhardwaj, the contents of which are incorporated, in their entirety,herein by reference. The manner in which the analyzer is used to providean indication of the integrity of the seal is generally described withrespect to the testing system disclosed in U.S. Pat. No. 6,343,510 toNeeson et al., the contents of which are also incorporated, in theirentirety, herein by reference.

One of the specific benefits of utilizing the analyzer system in theairborne contact or non-contact ultrasonic inspection systems is thatthe analyzer may be educated by passing seals of known integrity throughthe testing systems. By allowing the analyzer to obtain signals whichare known to be good, the analyzer develops a data base of signals whichare indicative of an effective seal. Likewise, by testing seals havingvarious known defects and depending on the type of package seal, theanalyzer's database can be keyed so as to effectively recognize whattype of defect is present in a seal. By way of example, by testing aseal having a known delamination, in a laminated type product, theanalyzer will know what types of signals are reflective of the specificdelamination. Further, if a delamination is detected during a testingprocedure, it will not only be possible to recognize the defect, but itis also possible to pinpoint the exact area of the defect.

With specific reference to FIG. 3A, a conveying system for the testsystem shown in FIGS. 1 and 2 is disclosed. The illustration shows atray “T” being filled at a filling station “F” and then passing by wayof conveyor “C” to the heat seal station “H” where the lid “L” isapplied and sealed. Thereafter, the container tray “T” is passed betweenthe transmitting and receiving transducers, 21 and 22.

In FIG. 3B, only a leading edge 30 and lagging edge 31 or zones of theseal are tested as the conveyor moves linearly past the transducers.Testing of only a portion of the seal, however, is not preferred in mosttesting procedures. In this embodiment, as opposed to only testing asegment of the seals, a plurality of spaced transmitting and receivingtransducers may be positioned, as shown in dotted line, about portionsof the container in order to ensure the entire length of the seal istested.

With specific reference to FIG. 4, a filled and sealed container in aform of a pouch “P” is disclosed which is carried by the conveyor “C”.The pouch includes an upper sealed area “S” which passes between thetransmitting transducer 21 and the receiving transducer 22 which arealigned so that ultrasonic energy from the transmitting transducer isdirected to the receiving transducer. In this embodiment, either one ofthe transducers may include a structure which serves to more directlyfocus the ultrasonic energy in a definable form. This is shown by theconcave face 35 of the receiving transducer 22. A like directing orfocusing can be provided by the transmitting transducer with a similarconfiguration.

One of the potential problems utilizing non-contact airborne ultrasonicenergy for testing is that it is possible, especially where a seal isimmediately adjacent into an edge of a package, that some of the energywill pass around the edge of the package or container, as is illustratedin dotted line 36 in FIG. 4. In order to prevent the interference of anywrap around energy with the receiving transducer, which could adverselyaffect a true reading of the integrity of the seal, with the presentinvention, the energy from the transmitting transducer may be otherwisefocused and screened relative to the edge “E” of the package.

To prevent such wrap around energy from adversely affecting thereceiving transducer and to maintain the package seal within the focalpoint between the transducers, a shield, head element or screen 40 maybe mounted so as to engage and overlap the upper edge “E” of thepackage, which may be the pouch “P”, as shown in FIG. 4. The screen 40is shown as being carried within a fixed housing 41 spaced above thepackage conveyor “C”. A spring or other resilient element 42 mountedwithin the housing allows the shield to be reciprocally movable alongits elongated axis “A” depending upon the size and spacing of the edge“E” of the pouch “P” so that, in effect, the shield 40 can track alongthe edge of the pouch, thus compensating for any difference in edgeconfiguration between one container and another. The shield 40 thusprevents any misdirected energy from being receivable by the receivingtransducer 22.

As opposed to the screen 40, a roller or wheel element 45 may be used tocreate a second barrier, as is shown in FIG. 6. The roller may also beresiliently mounted within a housing 46. A spring or other resilientmember 47 provides sufficient force to cause the roller to positivetrack along the edge of a package

With further reference to FIG. 6, the pouch “P” shown in FIG. 5 ismounted within a carrier 50 having a slot or cavity 51 therein in whichthe pouch is selectively seated. The carrier may include a centralopening 52 in the lower portion of the slot to allow drainage of fluidsor other elements which may enter into the slot. The slot in the carrieris of a size to cradle a portion of the bottom of the pouch and thusstabilize the pouch as it passes through the testing station 20 so thatthe seal “S” is appropriately aligned between the transmittingtransducer 21 and the receiving transducer 22.

With specific reference to FIG. 8, a variation of the embodiment shownin FIG. 5 is disclosed wherein the transmitting transducer 21 is mountedgenerally parallel to the receiving transducer 22. In this embodiment,the supports 28 and 29 are mounted generally in line with one another onopposite sides of the shield 40. Energy from the transmitting receiveris directed towards a parabolic reflector surface 55 which directs theenergy through the seal area “S” of the pouch “P”. The energy passesthrough the seal and is directed by parabolic reflective surface 56 tothe receiving transducer 22. The parabolic reflective surfaces can beutilized to effectively aim or direct the energy between thetransmitting and receiving transducers.

With reference to FIG. 9 a further method of shielding or preventingwrap around energy from reaching the receiving transducer is disclosed.In this embodiment, a barrier plate 60 is mounted between the seal area“S” of the pouch “P” such that all energy issuing from the transmittingtransducer 21 must pass through a circular or other shape of opening 62formed in the barrier plate. The opening 62 will focus the ultrasonicenergy directly through the seal area “S” and prevent any wrap aroundenergy from reaching the receiving transducer 22.

With reference to FIG. 10, another variation of the embodiment of theinvention shown in FIG. 5 is disclosed. In this embodiment, wrap aroundenergy is prevented from reaching the receiving transducer 22 byproviding a generally stationary guide channel housing 70 which ispositioned above the conveyor “C” on which the pouch “P” is carried. Thehousing includes opposite aligned openings 71 and 72 in which thetransmitting transducer 21 and the receiving transducer are mounted soas to be in open communication with one another. The space between thetransducers permits ultrasonic energy to pass through air or othergaseous medium from the transmitting transducer toward the receivingtransducer. The guide channel further includes an upper groove 74 inwhich the upper edge of the pouch is received such that no sound wavespass around the upper edge which would effect the amount of energy beingreceived by the receiving transducer 22. Therefore, all ultrasonicenergy must pass through the seal “S”. As shown, the housing alsoincludes an open slot 75 in which the upper portion of the pouch isguided as it passes through the channel housing 70. As opposed to thefixed slot or groove 74 in the embodiment in FIG. 10, a resilientlymounted member, such as shown at 40 in the embodiment in FIG. 5, or aroller, as shown at 45 of FIG. 6, can be used and mounted within thehousing 70.

With specific reference to FIG. 11, a top cross sectional view of anembodiment, similar to that disclosed in FIG. 10, is shown wherein thehousing 70 includes a pair of guide members 80 and 81 which are mountedwithin cavities 82 and 83, respectively, of the housing and which areresiliently urged by springs 84 toward the slot 75 and the upper edge ofthe pouch “P”. The spring loaded guides serve to orient and properlyposition the upper edge of the pouch such that the seal is alignedbetween the transmitting transducer 21 and the receiving transducer 22.As shown in FIG. 11, the pouches are carried by an appropriate conveyingdevice so as to pass sequentially through the testing device.

A variation of the embodiment shown in FIGS. 10 and 11 is shown in FIG.12. In this embodiment, the pouch “P” is being carried by a conveyorbelt system 90 which is positioned at an angle with respect tohorizontal, as shown at α. The housing 70 for mounting the transmittingand receiving transducers 21 and 22 is also mounted at an angle suchthat the edge “E” of the pouch engages within the slot or groove 74which serves to prevent wrapping of energy between the transmitter andreceiver.

In this embodiment, the pouch is guided and further stabilized by aplate 92 which may be resiliently urged by springs 94 towards the pouch.The plate is mounted withing a housing 93. The plate 92 insures that thepouch is positively guided and properly aligned as it passes through thechannel housing 70 so as to insure that the seal area “S” of the pouchis properly aligned between the transmitting transducer and thereceiving transducer.

A further embodiment of the invention is shown in FIG. 13, which issimilar to that shown in FIG. 1. In this embodiment, the transmittingtransducer and receiving transducer are mounted to a common support 96which is generally formed in a u-shape including opposite parallel legs97 and 98 which extend from a common base 99. Opposite the base 99, thesupport includes aligned arm segments 100 and 101 which are spacedrelative to one another so as to define a guide channel 102 therebetweenthrough which the seal and upper edge of a package extends as the sealarea passes between the transmitting transducer and the receivingtransducer 22. Although only one set of transducers is shown in thedrawing figure, it is possible that several sets may be carried by acommon support. Further, the support 96 may be carried by a separateconveying device such that the support moves relative to the package orpouch rather than the pouch moving relative to the testing transducers.

Further although not shown in FIG. 13, an appropriate shield could alsobe provided to prevent energy from passing over the edge of the package,as previously described with respect to the other embodiments of theinvention.

With particular reference to FIGS. 14 and 15, another variation ofinspection station is shown. In this embodiment, the packages or pouches“P” are not only carried on a conveyor as previously described, they arealso positively guided and aligned relative to a passage 121 in aninspection head 120 by opposing side conveyors 122 and 123. Theinspection head includes two sections 124 and 125 each having a cavity126 and 127 therein, respectively. The cavities are closed by transducermounting plates 128 and 129 in which one or more transmittingtransducers 21 and receiving transducers 22 are adjustably mounted.However, the cavities are in communication through openings 130 in thesections 124 and 125.

In the present embodiment, the ultrasonic energy is focused toward theseal area “S” of the packages as the edge of the package is guidedwithin the slot or passage 121. Focusing is provided by adjustableelements 132 having focal openings 134 therein. Energy from thetransmitting transducer is guided through the focal openings and thusprevents sound waves from being misdirected toward the receivingtransducer. Further, the focal elements 132 may be resiliently movableby springs or like devices 136 so as to be automatically adjusted fordifferent package sizes or thicknesses adjacent the package seals. Also,the force provided by the springs can be adjusted by screws or otheradjustment members 138. In this embodiment, protruding portions 140 ofthe focal elements may contact the surface of the packages adjacent theseals as shown in the drawing figures.

With respect to FIG. 16, a variation of the non-contact airborneultrasonic testing systems previously disclosed is shown. In theembodiment of FIG. 16, the transmitting transducer 21 is showing asbeing in contact with the pouch “P” adjacent to the seal area “S” duringthe testing. Ultrasonic energy which passes through the seal area isreceived by the receiving transducer 22 which is spaced at a distancefrom the seal in a gaseous environment, such as ambient air.

FIG. 17 is a variation of contact airborne ultrasonic testing orinspecting in accordance with the present invention wherein thereceiving transducer 22 is shown as being in contact with the package orpouch “P” adjacent to the seal “S”. Ultrasonic energy is transmittedtoward the seal area by a transmitting transducer 21 which is spaced innon-contact relationship with respect to the package or pouch.

A further variation of the present invention is disclosed in solid linein FIG. 18 wherein a transmitting transducer 21′ also functions as areceiving transducer. In this embodiment, ultrasonic energy from thetransmitting transducer 21′ is directed at the seal area “S” of thepackage “P”. Such energy is reflected and subsequently detected by thetransmitting transducer which is electrically controlled to alsofunction as a receiving transducer to record the amount of reflectedenergy from the seal area “S”. This type of system would generally bedescribed as a pulse-echo type system.

A variation of pulse-echo system is shown in dotted line in FIG. 18wherein the transmitting transducer 21 is mounted so as to directultrasonic energy toward the seal area “S” with energy being reflectedand detected by the receiving transducer 22 which is mounted on the sameside of the seal area as the transmitting transducer.

A further variation of the present invention is shown in FIG. 19. Inthis variation, the transmitting transducer is movable and is formed asa rotatable wheel 110 mounted to a support assembly 112. The wheel isallowed to roll along a portion of the package “P” adjacent to the sealarea “S” during testing or inspecting with the amount of acoustic energypassing through the seal area being detected by the receiving transducer22. Although not shown in the drawings, the receiving transducer mayalso be formed as a wheel-like element similar to that as shown at 110.

The foregoing description of the preferred embodiment of the inventionhas been presented to illustrate the principles of the invention and notto limit the invention to the particular embodiment illustrated. It isintended that the scope of the invention be defined by all of theembodiments encompassed within the following claims and theirequivalents.

1. A method for inspecting a package seal of a package using an airborneultrasonic system including at least one airborne ultrasonictransmitting transducer and at least one airborne ultrasonic receivingtransducer, the method including, in a gaseous environment, mounting theat least one airborne ultrasonic transmitting transducer on one side ofthe package seal and mounting the at least one airborne ultrasonicreceiving transducer on an opposite side of the package seal, providingrelative movement between a package and said at least one airborneultrasonic transmitting transducer and said at least one airborneultrasonic receiving transducer so that the package moves between the atleast one airborne ultrasonic transmitting transducer and the at leastone airborne ultrasonic receiving transducer, directing ultrasonicenergy in a non-liquid environment toward the package seal from the atleast one airborne ultrasonic transmitting transducer to the at leastone airborne ultrasonic receiving transducer as there is relativemovement therebetween while preventing ultrasonic energy from passingabout an edge of the package adjacent the seal toward the at least oneairborne ultrasonic receiving transducer, and using the energy receivedat the at least one airborne ultrasonic receiving transducer to providea signal to a device to thereby obtain an indication of integrity of theseal.
 2. The method of claim 1 including mechanical focusing theultrasonic energy issued from the at least one airborne ultrasonictransmitting transducer as the ultrasonic energy is directed toward theseal.
 3. The method of claim 2 wherein the focusing includes conveyingthe seal within an open channel in which the at least one airborneultrasonic transmitting transducer and the at least one airborneultrasonic receiving transducer are mounted in spaced relationship toone another so as to be on opposite sides of the seal.
 4. The method ofclaim 2 wherein the mechanical focusing includes passing the ultrasonicenergy from the at least one airborne ultrasonic transmitting transducerthrough an opening in a sound barrier toward the seal.
 5. The method ofclaim 1 including providing a sound barrier along the edge of thepackage adjacent the seal to thereby prevent the ultrasonic energy frompassing about the edge of the package toward the at least one airborneultrasonic receiving transducer.
 6. The method of claim 5 includingresilient urging the sound barrier toward the edge of the package. 7.The method of claim 1 wherein the at least one airborne ultrasonictransmitting transducer and the at least one airborne ultrasonicreceiving transducer are spaced in non-contact relationship from thepackage.
 8. A method for inspecting a package seal adjacent an edge of apackage using an airborne ultrasonic system including at least oneairborne ultrasonic transmitting transducer and at least one airborneultrasonic receiving transducer, the method including, in a gaseousenvironment, directing ultrasonic energy toward the package seal fromthe at least one airborne ultrasonic transmitting transducer to the atleast one airborne ultrasonic receiving transducer, preventing theultrasonic energy directed toward the package seal from passing about anedge of the package adjacent the seal toward the at least one airbornereceiving transducer, and using the energy received at the at least oneairborne ultrasonic receiving transducer to provide a signal to a deviceto thereby give an indication of integrity of the seal.
 9. The method ofclaim 8 including providing a sound barrier along the edge adjacent theseal to prevent ultrasonic energy from passing about the edge of thepackage toward the at least one airborne ultrasonic receivingtransducer.
 10. The method of claim 9 including resiliently urging thesound barrier toward the edge adjacent the seal of the package.
 11. Themethod of claim 8 including conveying the package relative to theairborne ultrasonic system so that the seal moves between the at leastone airborne ultrasonic transmitting transducer and the at least oneairborne ultrasonic receiving transducer as ultrasonic energy isdirected toward the seal.
 12. The method of claim 8 including mechanicalfocusing the ultrasonic energy from the at least one airborne ultrasonictransmitting transducer toward the seal.
 13. The method of claim 12wherein the mechanical focusing includes passing the ultrasonic energyfrom the at least one airborne ultrasonic transmitting transducerthrough an opening in a sound barrier toward the seal.
 14. The method ofclaim 8 including mounting the at least one airborne ultrasonictransmitting transducer on one side of the package seal and mounting theat least one airborne ultrasonic receiving transducer on an oppositeside of the package seal, and focusing the ultrasonic energy byconveying the seal within an open channel on either side of which saidat least one airborne ultrasonic transmitting transducer and at leastone airborne ultrasonic receiving transducer are mounted in spacedrelationship to one another.
 15. The method of claim 14 includingresiliently urging a sound barrier toward the edge of the package. 16.The method of claim 14 including providing a sound barrier along theedge adjacent the seal to prevent ultrasonic energy from passing aboutthe edge of the package toward the at least one airborne ultrasonicreceiving transducer.
 17. The method of claim 8 including moving said atleast one airborne ultrasonic transmitting transducer and said at leastone airborne ultrasonic receiving transducer relative to the packageseal.